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drm/i915: Protect access to driver and timeline name

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Protect the access to driver and timeline name which otherwise could be
freed as dma-fence exported is signalling fences.

This prepares the code for incoming dma-fence API changes which will start
asserting these accesses are done from a RCU locked section.

Now that the safe access is handled in the dma-fence API, the external
callers such as sync_file, and our internal code paths, we can drop the
similar protection from i915_fence_get_timeline_name().

This prepares the code for incoming dma-fence API changes which will start
asserting these accesses are done from a RCU locked section.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com> # v1
Signed-off-by: Tvrtko Ursulin <tursulin@ursulin.net>
Link: https://lore.kernel.org/r/20250610164226.10817-3-tvrtko.ursulin@igalia.com
This commit is contained in:
Tvrtko Ursulin
2025-06-10 17:42:24 +01:00
committed by Tvrtko Ursulin
parent ad10976d6c
commit 4d2f8bc628
3 changed files with 21 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/gpu/drm/i915/gt/intel_gt_requests.c
View File

@@ -250,11 +250,17 @@ void intel_gt_watchdog_work(struct work_struct *work)
llist_for_each_entry_safe(rq, rn, first, watchdog.link) {
if (!i915_request_completed(rq)) {
struct dma_fence *f = &rq->fence;
const char __rcu *timeline;
const char __rcu *driver;
rcu_read_lock();
driver = dma_fence_driver_name(f);
timeline = dma_fence_timeline_name(f);
pr_notice("Fence expiration time out i915-%s:%s:%llx!\n",
dma_fence_driver_name(f),
dma_fence_timeline_name(f),
rcu_dereference(driver),
rcu_dereference(timeline),
f->seqno);
rcu_read_unlock();
i915_request_cancel(rq, -EINTR);
}
i915_request_put(rq);

7
drivers/gpu/drm/i915/i915_request.c
View File

@@ -2184,7 +2184,7 @@ void i915_request_show(struct drm_printer *m,
const char *prefix,
int indent)
{
const char *name = dma_fence_timeline_name((struct dma_fence *)&rq->fence);
const char __rcu *timeline;
char buf[80] = "";
int x = 0;
@@ -2220,6 +2220,8 @@ void i915_request_show(struct drm_printer *m,
x = print_sched_attr(&rq->sched.attr, buf, x, sizeof(buf));
rcu_read_lock();
timeline = dma_fence_timeline_name((struct dma_fence *)&rq->fence);
drm_printf(m, "%s%.*s%c %llx:%lld%s%s %s @ %dms: %s\n",
prefix, indent, " ",
queue_status(rq),
@@ -2228,7 +2230,8 @@ void i915_request_show(struct drm_printer *m,
fence_status(rq),
buf,
jiffies_to_msecs(jiffies - rq->emitted_jiffies),
name);
rcu_dereference(timeline));
rcu_read_unlock();
}
static bool engine_match_ring(struct intel_engine_cs *engine, struct i915_request *rq)

10
drivers/gpu/drm/i915/i915_sw_fence.c
View File

@@ -430,16 +430,22 @@ static void timer_i915_sw_fence_wake(struct timer_list *t)
struct i915_sw_dma_fence_cb_timer *cb = timer_container_of(cb, t,
timer);
struct i915_sw_fence *fence;
const char __rcu *timeline;
const char __rcu *driver;
fence = xchg(&cb->base.fence, NULL);
if (!fence)
return;
rcu_read_lock();
driver = dma_fence_driver_name(cb->dma);
timeline = dma_fence_timeline_name(cb->dma);
pr_notice("Asynchronous wait on fence %s:%s:%llx timed out (hint:%ps)\n",
dma_fence_driver_name(cb->dma),
dma_fence_timeline_name(cb->dma),
rcu_dereference(driver),
rcu_dereference(timeline),
cb->dma->seqno,
i915_sw_fence_debug_hint(fence));
rcu_read_unlock();
i915_sw_fence_set_error_once(fence, -ETIMEDOUT);
i915_sw_fence_complete(fence);